Schedule III - Income Statement Captions (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplementary Insurance Information By Segment [Line Items]
Premiums and escrow fees		$ 4,701.4	$ 6,632.4	$ 7,355.5
Net investment income (1)	[1]	363.6	(175.7)	650.4
Loss provision		336.3	486.3	588.7
Amortization of deferred policy acquisition costs (credits)		(0.2)	4.3	10.8
Other operating expenses		1,067.0	1,272.3	1,322.9
Premiums written		398.4	393.9	449.9
Operating Segments | Title Insurance and Services
Supplementary Insurance Information By Segment [Line Items]
Premiums and escrow fees		4,305.7	6,210.5	6,858.0
Net investment income (1)	[1]	502.0	209.3	259.9
Loss provision		139.9	248.4	274.4
Amortization of deferred policy acquisition costs (credits)		0.0	0.0	0.0
Other operating expenses		937.7	1,155.4	1,197.7
Premiums written		0.0	0.0	0.0
Operating Segments | Home Warranty
Supplementary Insurance Information By Segment [Line Items]
Premiums and escrow fees		395.6	413.1	399.8
Net investment income (1)	[1]	(0.1)	(7.4)	11.2
Loss provision		193.1	211.8	218.2
Amortization of deferred policy acquisition costs (credits)		(0.2)	1.9	(5.3)
Other operating expenses		82.8	75.7	61.5
Premiums written		398.4	394.9	412.6
Operating Segments | Corporate and Eliminations
Supplementary Insurance Information By Segment [Line Items]
Premiums and escrow fees		0.1	8.8	97.7
Net investment income (1)	[1]	(138.3)	(377.6)	379.3
Loss provision		3.3	26.1	96.1
Amortization of deferred policy acquisition costs (credits)		0.0	2.4	16.1
Other operating expenses		46.5	41.2	63.7
Premiums written		$ 0.0	$ (1.0)	$ 37.3

[1] Includes net investment income and net investment gains (losses).